MIPS: Eliminate Smi check when changing from Smi to Integer32

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index 18e89ddd5c047bd2beaf90b67b0678378af060fa..8249391c9a56c3dd76fef41c75a0f3720a4a127f 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1828,11 +1828,12 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       ASSERT(to.IsInteger32());
       LOperand* value = NULL;
       LInstruction* res = NULL;
-      if (instr->value()->type().IsSmi()) {
-        value = UseRegisterAtStart(instr->value());
+      HValue* val = instr->value();
+      if (val->type().IsSmi() || val->representation().IsSmi()) {
+        value = UseRegisterAtStart(val);
         res = DefineAsRegister(new(zone()) LSmiUntag(value, false));
       } else {
-        value = UseRegister(instr->value());
+        value = UseRegister(val);
         LOperand* temp1 = TempRegister();
         LOperand* temp2 = instr->CanTruncateToInt32() ? TempRegister()
                                                       : NULL;